Created module idea-test-framework and moved classes needed for idea tests there

Moved tests for completion and their test data into module idea-completion

idea/idea-completion/testData/handlers/runtimeCast/CastPrivateFun.kt

@@ -0,0 +1,14 @@
+fun main(args: Array<String>) {
+    val b: A = C()
+    <caret>val a = 1
+}
+
+open class A
+open class B {
+    private fun funInB() {}
+}
+
+class C: B()
+
+// INVOCATION_COUNT: 2
+// RUNTIME_TYPE: C